CMOS technology is used to construct integrated circuits such as microprocessors, microcontrollers, static random access memory (SRAM) and other digital logic circuits. By virtue of continued scaling of device technologies, interconnect structures need to be reduced in size. For example, interconnect structures with dimensions of less than 30 nm are now required in many semiconductor processes.
As the devices are scaled to smaller dimensions, various designs and techniques are employed to improve device performance. For example, as the interconnect structures scale downwards, different metals or metal alloys are required with lower resistivities and better electromigration properties in order to improve device performance. Such metals, because of better electromigration properties, may not need barrier liners, which will allow interconnects made from them to have lower electrical resistance, as critical dimensions shrink, than conventionally used metals.